Mapping pressurized volcanic fluids from induced crustal seismic velocity drops

Mapping pressurized volcanic fluids from induced crustal seismic velocity drops

F. Brenguier1, M. CampilloT. TakedaY. AokiN. M. Shapiro

X. BriandK. EmotoH. Miyake

Science, vol. 345, 80-82, doi:10.1026/science.1254073

Abstract

Volcanic eruptions are caused by the release of pressure that has accumulated due to hot volcanic fluids at depth. Here, we show that the extent of the regions affected by pressurized fluids can be imaged through the measurement of their response to transient stress perturbations. We used records of seismic noise from the Japanese Hi-net seismic network to measure the crustal seismic velocity changes below volcanic regions caused by the 2011 moment magnitude (Mw) 9.0 Tohoku-Oki earthquake. We interpret coseismic crustal seismic velocity reductions as related to the mechanical weakening of the pressurized crust by the dynamic stress associated with the seismic waves. We suggest, therefore, that mapping seismic velocity susceptibility to dynamic stress perturbations can be used for the imaging and characterization of volcanic systems.

図:応力変化に対する地震波速度変化の感度の空間分布。東北地方太平洋沖地震にともなう地震波速度変化と、全地球測位システム(GNSS)による観測により求められるひずみ変化から求められています。黒い三角形は第四紀火山の分布を、赤線は火山フロントを表します